1. Field of the Invention
The present invention relates to systems which provide, during the in situ pouring of concrete, work holders for the accurate location of elements to-be-embedded in concrete. More specifically, it relates to a reusable system including at least two rails and at least one element locating plate which is attached to and supported by the rails to accurately locate the plate at any location within a concrete form.
2. Description of the Prior Art
In many types of construction operation utilizing concrete, it is necessary or desireable to locate a work element, such as an anchor bolt, in the concrete. The accuracy required in the location of the work element varies from job to job. Many construction jobs require the precise positioning of work elements, both as to their specific location within the concrete, and also with respect to their location to other work elements. It has been common practice in the art, where precise location of one or more element in concrete is required, to rig a template, for example of plywood, boards, or other building materials, then to precisely drill or cut holes in the template which correspond as nearly as possible to the desired location of each work element, secure each work element to the large template, place the entire template and the work elements which it carries over a concrete form, secure it for example by nailing it to the form, and then pour concrete into the form. Such systems have their limitations. Several problems arise when the concrete is poured. For example, during the pouring of concrete to secure anchor bolts, the bolts often tend to rotate, gradually rising or sinking in the concrete, thus eventually being set at the wrong level. Additionally, the force, pressure, and weight of the concrete often tends to skew bolts out of the vertical and it is usually impossible, once all the concrete has been poured, to straighten the bolts by twisting the small portion which remains above the concrete surface. Additionally, such large wooden templates often make it difficult, or impossible to properly finish the top surface of the concrete. Furthermore, such prior art templates require a great deal of time and material to produce, are large and cumbersome to work with, and normally have utility for but a single concrete job. Seldom in any two pours is the pattern and size of work elements to-be-located in the concrete duplicated. Thus, these prior art templates have utility for only one pour and their normal disposition has been to the scrap heap after one use.
Such systems have been especially needed where anchor bolts embedded in concrete are used to support and secure structures, including buildings bridges, and machinery. In such applications, it is important that the anchor bolts be previously and accurately cast into concrete to accept, secure, and support the structure or device. Failure to locate the bolts accurately both with respect to one another, or with respect to the entire concrete surface, makes it difficult to seat and secure equipment or steel having premachined openings. As already noted, accurate location of bolts, for such purposes, has in the past required a great deal of time and has been relatively expensive in terms of the types of materials which have been utilized, the labor required to produce them, and the lack of reusability of the template.
Efforts have been made to provide smaller or reusable locating means for elements to be located in concrete. For example, U.S. Pat. No. 1,199,077 provides means for locating an anchoring element within concrete. However, the locating means taught in that reference remains in the concrete and is not reusable. U.S. Pat. No. 3,304,079 discloses a complex mechanical system for holding bolts during concrete formation. U.S. Pat. No. 3,468,184 discloses a collapsible cardboard system for use in positioning and aligning anchor bolts in concrete. However, such positioners require individual machining to locate each element. U.S. Pat. Nos. 3,150,429 and 3,552,734 are of interest as disclosing means for locating anchor bolts around the periphery of a concrete pour, while U.S. Pat. No. 3,912,218 discloses a method of locating bolts for hand rails at the edges of stairs. However, none of these systems discloses an inexpensive, non-consumed, reusable, universal locating system for anchor bolts or other work elements, which system is capable of locating elements accurately at any location within a pour.
U.S. Pat. No. 3,219,308 is of interest as disclosing a complex system for locating forms in concrete piers or columns. However, it does not provide for precise anchor bolt location. Anchor bolt location is accomplished by means such as a transit or level. U.S. Pat. No. 3,960,356 is of particular interest as disclosing a system which allows a great deal of discretion in the size and shape of elements to-be-located at almost any location. Unfortunately, by its nature, it is limited to small forms, and does not provide for accurate location of more than one element with respect to another element.
In order for a system to provide anchor bolt location, while overcoming the problems of the prior art, it must be relatively small, portable, light weight, and substantially capable of accepting almost any size and shape of element to be located in concrete. It should also be capable of locating such elements securely so that they neither drift, change elevation, nor tilt. It should also be capable of being reused. Additionally, it should be easily stored in a small space, readily set up at a building site to precisely locate the elements at their required positions and spaces during the concrete pouring and setting operations, and it should thereafter be readily disengageable from the element and easily disassemblable for storage until needed again.